Colonoscopy

Colonoscopy is a procedure used to examine or inspect the bowel (large intestine or colon).

A colonoscopy allows for a variety of operations to be carried out through a colonoscope.

These operations may include taking a small tissue sample (biopsy) and removal of polyps.

Terms explained

Colonoscope – a long, firm plastic tube with a tiny camera that allows the doctor see a clear view of the colon lining.

Polyp – a growth on the lining of the colon. These growths can be benign, but can sometimes become cancerous later.

Why am I having a colonoscopy?

Patients have colonoscopy for several reasons. For example, there may be symptoms such as:

bleeding

altered bowel habit

pain suggesting a disorder of the bowel.

Alternatively, it may be done as a screening test for cancer or polyps in people without symptoms.

What are the benefits?

An alternative method of examining the large bowel is X-ray tests. Colonoscopy has the advantage over X-ray tests of generally being more accurate for detecting diseases of the bowel, and also of allowing tissue samples or biopsies to be taken and polyps removed.

Colonoscopy is the most accurate test for detecting polyps and is very accurate for detecting bowel cancer. Surveys suggest the risk of not detecting cancer is less than 1 in 200.

Are there any risks?

Complications of colonoscopy, such as perforation (making a hole in the bowel wall) or major bleeding, are very uncommon. When the examination only inspects the bowel wall and does not involve removal of polyps, most surveys report complications in less than 1 in 2000 examinations.

When polyps are removed (about one-third of examinations), the risk is greater – perforation may occur in about 1 in 400 examinations and bleeding requiring hospitalisation and blood transfusion in about 1 in 1000 examinations.

Please note that because of the risk of polyps developing into cancer, it is recommended that all polyps are removed if possible during the colonoscopy; it is still safer to do this than leave polyps behind.

Complications of sedationare also uncommon and include difficulty breathing and abnormal heart rhythms. Serious sedation reactions may be more common in patients with severe heart or chest disease. These complications are usually avoided by administering oxygen during the procedure and monitoring the oxygen level in the blood.

How do I prepare for a colonoscopy?

It is important to follow closely the instructions you are given to fully prepare your bowel for the colonoscopy.

Prior to the colonoscopy you should obtain a ‘bowel preparation’ kit. For a few days before the procedure, you will need to follow special diet, called a low residue diet.

You will then be asked to take a laxative and then to drink a quantity of mildly salty tasting solution which completely cleanses the colon.

The bowel preparation solution may cause some nausea (feeling sick) and bloating, though this usually passes with continued drinking.

While drinking the bowel preparation solution, you will need to stay close to toilet facilities.

Very occasionally, people may feel very light-headed or may even collapse while drinking the bowel preparation solution. If this happens you should stop the bowel preparation and seek medical attention.

Tell your doctor before the procedure if you:

are sensitive (allergic) to any drug or substance

are taking medication for arthritis such as aspirin

are taking blood thinning tablets such as Warfarin

have heart valve disease or have a pacemaker.

If you are taking aspirin or NSAIDS (arthritis tablets) there is little or no increased risk of bleeding from the colonoscopy.

If you are taking clopidogrel (Iscover® or Plavix®) within the week prior to colonoscopy, there may be an increased risk of bleeding from colonoscopy. You should discuss with your doctor whether it is safe for you to temporarily withhold any of these medications, or whether you should be seen by a gastroenterologist in advance of the procedure.

You should inform your doctor if you are taking other blood thinning tablets, such as Warfarin, as arrangements to cease this medication are usually required prior to colonoscopy.

You should cease iron tablets and any medication used to stop diarrhoea at least 5 days before the procedure.

On the day of the procedure

Report to the hospital as outlined in your referral letters.

What happens during a colonoscopy?

You will be given a sedative injection through a vein in your arm before the procedure to make you more comfortable.

Doctors will then gently insert the colonoscope through your back passage (anus) and into the large intestine to allow inspection of the whole of the large bowel.

As cancer of the large bowel arises from pre-existing polyps it is advisable that any polyps found should be removed at the time of the examination. Most polyps are burnt off (this is called polypectomy) by placing a wire snare around the base and applying an electric current.

During the examination there may be some cramp-like discomfort in the abdomen, though this is usually of very short duration and minimised by the sedative.

Most patients do not report significant discomfort from the colonoscopy examination, and in fact most report the bowel preparation drink as the most difficult part of the entire process of colonoscopy.

What happens afterwards?

Any sedative you are given before the procedure is very effective in reducing discomfort. However, it may also affect your memory for a few hours afterwards. Even when the sedative appears to have worn off, you may find that you are unable to recall details of your discussion with the doctor and nursing staff. For this reason a relative or friend should come with you if possible.

For your personal safety following the sedated procedure, we strongly encourage a friend or relative to escort you from the day ward and drive you home.

After the sedative you should not:

drive a car for 24 hours

operate machinery for 24 hours

sign any legal documents until the next day.

undertake any other activities likely to place you at risk.

The vast majority of patients having a colonoscopy with sedation do not return to work on the day of the examination.

Following the procedure you may have minor abdominal discomfort for up to 24 hours. However, if you have any severe abdominal pain, or bleeding from the back passage, or any other symptoms that cause you concern you should contact:

the hospital where you had your colonoscopy

your GP.

When will I get the results?

The amount of time it takes for you to get your results will differ depending on where you have the procedure done. The specialist will write a report, which may include pictures. The pictures may be on films or on a CD.

Ask whether you should wait to take the report with you, or whether it will be sent to your doctor.

Your doctor will need to discuss the report with you. You may need to make an appointment to do this.

Where to get help

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.